Oil companies claim there are enough proven oil reserves to last the world 40 years at the currently level of consumption. Scientists however take a different view, some of them warning that global oil production will peak within the next four years.

“Peak Oil” is the theoretical point where the discovery of new oil reserves will be outstripped by the consumption of those already discovered. The theory is that this would cause oil prices to spiral out of control and cause oil dependent economies to grind to a halt.

For environmentalists the approach of peak oil could be an opportunity to push cleaner technologies. But with if there is little time left it is likely that coal will be used to replace oil, probably increasing greenhouse gas emissions in the process.

In the short term the advice therefore is to limit demand for oil by boosting efficiency. The time this buys should be used to develop more alternatives. As they become a reality these alternatives will stretch the time until peak oil further, and provide a cleaner basis for a healthy economy in the future.

For more on peak oil read these stories from The Independent and Business Week